Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Competition between wheat and associated weeds at different nitrogen rates.

Abstract

Field trials were conducted over 2 consecutive winters to evaluate the effects on weed competition in wheat cv. WH-329 on sandy loam of 0-120 kg/ha N (50% supplied at sowing and 25% at each of the first and second irrigations) and post-em. treatment at 31 or 36 d after sowing (DAS) with 1.0 kg/ha isoproturon ± 0.5 kg 2,4-D or 0.75 kg isoproturon + 0.1% Teepol surfactant. Isoproturon + 2,4-D resulted in absolute weed control, whereas the other herbicides increased the DW ratio of wheat:weeds from 9.5-11.1 to 23.1-27.1 and 4.5-4.9 to 12.5-16.0 in the 2 years. N concn had no effect on the ratio or on that of wheat:wild oat [Avena spp.] which varied from 0.9 to 1.6 at harvest and was generally higher at low Avena densities (45 plants/m2). The DW of broadleaved weeds (mainly Chenopodium album, Anagallis arvensis, Melilotus alba and Vicia sativa) increased to a max. of 40-60 g/m2 at 90 DAS, whereas that of Avena rose sharply at 60 DAS to 250-400 g at harvest. In wheat the concn of N was correlated with the height and number of shoots, and yield with ear length and number of spikelets/spike.